Currently there is a lack of a fast, efficient, and scalable manufacturing process for adding micro-features to electrode systems. Wet and dry etching processes have been employed with various degrees of success. Dry etching typically consists of performing an oxygen plasma etching process over the underlying structure. Plasma etching has been successfully applied to improve the response of electrochemical sensors through an increase of their hydrophilicity. However, this technique will only increase the access of the solution to small porosities already available in the underlying base material, but will not significantly affect total surface area (e.g., features size is too small). Another option may be found on electrochemical pretreatment (ECP), however, exposing a conductive structure to a DC potential while immersed in a basic solution causes breakage in the structure, causing permanent damage. A competing approach is to develop three-dimensional (3D) structures, such as posts or walls with high aspect ratio that increase the surface area; examples include, but are not limited to, arrays of posts and multilayer structures. U.S. Patent Application Publication No. 2011/0203936, for example, discloses a method of making polymer-based high surface area multi-layered three-dimensional structures.
Further patterning of these three-dimensional structures might include organic beads deposited on the substrate from a liquid phase. When the liquid solution evaporates the beads are left on the surface, but the attachment is very weak and beads soon fall out. Various techniques have also been employed to increase the surface area by producing etch pits of controlled geometry. Several of the processes listed above suffer from limitations and drawbacks such as damage of the structures, long processing time, insufficient control over the desired features, complexity of the processes, and high energy consumption.